Unpaid Refund for building insurance

I have been in talks with Outsurance for close to three months regarding a building insurance refund that's due to me. I have been paying double insurance for my building and after weeks of talking Outsurance agreed to pay the refund. After submitting papers and supporting docs, they only refunded a portion of the full refund stating they can't release the other refund as the supporting documents are not aligned. I explained I cannot get the supporting docs as the company closed down. I was advised to submit a letter from the current estate managers to state that they took over the account and it had been previously insured. I did all of that and now I am being sent from pillar to post if I'm lucky to get feedback from Outsurance! They take their sweet time to get back to me or rather, they don't get back to me at all, I have to harass them for feedback. This is totally uncalled for and unprofessional! I'm highly irritated and upset at the level of service received when I look at the premiums I'm paying. I'm highly disgusted, still don't have feedback!